Evaluation of Preemergence Herbicides for Crop Safety and Weed Control in Safflower

Abstract

Weed management in safflower (Carthamus tinctorious L.) is a major challenge for growers due to very limited herbicide options available, particularly for broadleaf weed control. Field experiments were conducted at the Montana State University Southern Agricultural Research Center (MSU-SARC) near Huntley, MT in 2015 and 2016 to evaluate preemergence (PRE) soil-residual herbicides for crop safety and season-long broadleaf weed control in safflower. Among all herbicide programs tested, only sulfentrazone (105 g•ai•ha −1) alone or with pendimethalin (1064 g•ai•ha −1) caused 4% to 12% early-season visible injury to safflower, although the injury was not evident beyond 30 DAT. Sulfentrazone alone or with pendimethalin and pyroxasulfone (59 g•ai•ha −1) with pendimethalin had a season-long residual activity on kochia [Kochia scoparia (L.) Schrad] and Russian-thistle (Salsola tragus L), with 89% to 99% control at 60 DAT, and up to 98% reduction in weed density compared with dimethenamid-P (213 g•ai•ha −1) and S-metolachlor (433 g•ai•ha −1) at 65 DAT. Pyroxasulfone (59 or 118 g•ai•ha −1) alone or dimethenamid-P with pendimethalin provided a moderate to good control (65% to 79% at 60 DAT) of kochia and Russian-thistle. However, the end-season control of kochia or Russian-thistle was inadequate (<50% control) with pendimethalin, dimethenamid-P, or S-metolachlor alone program. Safflower grain yield with sulfentrazone alone or with pendimethalin, pyroxasulfone alone or with pendimethalin, and dimethenamid-P with pendimethalin averaged 3559 kg•ha −1 , which was 195% higher compared with the nontreated check. In conclusion, sulfentrazone and pyroxasulfone or dimethenamid-P in combination with pendimethalin will be effective PRE herbicide programs for kochia and Russian-thistle control in safflower.

Determination of The Efficacy of Some Herbicides on the Weeds in Safflower

“…Weed control efficacy of pendimethalin has declined throughout the growing season, but s-metolachlor's relatively remained stable. The findings of our study are similar to Jha et al (2017). Atanasova and Marcheva (2015) have also indicated that pendimethalin provided the highest herbicide effectiveness, but the efficacy of s-metolachlor was limited because it has a strong effect on grass weed and a limited on some broadleaves weeds.…”

“…Similar to pendimethalin, s-metolachlor controlled redroot pigweed at the highest rates, but weed control efficacy of s-metolachlor continued throughout the season. Jha et al (2017) have determined that pendimethalin and s-metolachlor at 1064 and 433 g ai ha -1 did not cause any injury on the safflower while they moderately and poor controlled Kochia and Russian-thistle, respectively. Weed control efficacy of pendimethalin has declined throughout the growing season, but s-metolachlor's relatively remained stable.…”

“…The data obtained from the experiments were subjected to analysis of variance, and the means were compared using Fisher's Least Significant Difference (LSD) test at a P value of 0.05 using SPSS statistical software (SPSS 2004). Before the statistical analyses, visual weed control and crop injury data were transformed using arcsine of the square root to normalize the variances within treatments; however, to make easily understand the original means are presented in the relevant tables ( Jha et al (2017) have determined that pendimethalin and s-metolachlor at 1064 and 433 g ai ha -1 did not cause any injury on the safflower while they moderately and poor controlled Kochia and Russian-thistle, respectively. Weed control efficacy of pendimethalin has declined throughout the growing season, but s-metolachlor's relatively remained stable.…”

Effects of Pre-Emergence Herbicides on Weed Control and Yield of Safflower (Carthamus tinctorius L.) in Central Italy

“…The results of this research showed that s-metolachlor, aclonifen, and propyzamide were the less injurious herbicides for safflower, confirming the results obtained in previous studies [9][10][11][12]17,18]. However, s-metolachlor seemed to be the best option to obtain a good efficacy against the main weeds in the trials, whereas aclonifen and propyzamide failed to control some weeds.…”

“…However, s-metolachlor seemed to be the best option to obtain a good efficacy against the main weeds in the trials, whereas aclonifen and propyzamide failed to control some weeds. Jha et al [17] have determined that pendimethalin and s-metolachlor at 1064 and 433 g a.i. ha −1 did not cause any injury on the safflower, while they moderately and poorly controlled Kochia scoparia (L.) Schrad and Salsola tragus L., respectively.…”